The present invention relates to recreational vehicles such as watercraft, personal watercraft (PWCs), all-terrain vehicles (ATVs), and snowmobiles. More particularly, the present invention relates to fluid flow in an engine of a vehicle.
A significant distinction between recreational vehicles such as watercraft, PWCs, ATVs, and snowmobiles and most other types of motorized xe2x80x9cvehicles,xe2x80x9d such as automobiles, is that recreational vehicles can be tipped over without a rider during operation and can be subsequently uprighted for continued operation. This is particularly true of personal watercraft (PWCs). A particular problem that can occur during inversion and/or uprighting of watercraft, such as PWCs, is that fluid in a system tends to flow in an undesired direction during inversion.
For example, in a typical four-stroke engine, the oil reservoir is located on the lower side of the engine and connects to an air escape port (which may be connected to the air intake system of the engine for recombustion and recycling or may be in communication with the environment via the watercraft""s exhaust system). As a result, oil in the reservoir, which is normally kept in the reservoir by gravity while the watercraft is upright, will disadvantageously flow upwardly within the engine, and possibly out through the exhaust port, when the engine is inverted. In the arrangement where the air escape port communicates with the environment, the oil could flow directly into the water. In the arrangement where the air escape port is communicated to the air intake system, the oil flowing out the air escape port will accumulate in the air intake system and may detrimentally affect engine performance.
Another example of such a problem can be found in the typical two-stroke engine in a watercraft. The two-stroke engine in a watercraft typically communicates with a dual muffler exhaust system in which the mufflers are positioned on opposing lateral sides of the watercraft. However, one of the mufflers may be replaced with a tuned pipe. A crossover pipe connects the two mufflers and extends up and over the tunnel in which the impeller is located. One of the mufflers is connected to the exhaust manifold on the engine (i.e., the proximal muffler) and the other muffler is communicated to the atmosphere by a discharge pipe (i.e., the distal muffler). When the watercraft is inverted, water may flow into distal muffler via the discharge pipe. When the watercraft is rotated about its longitudinal axis to its upright position in a xe2x80x9ccorrectxe2x80x9d rotational direction, the water in the distal muffler will be forced against the wall of the muffler and will remain therein. However, if the watercraft is rotated in the opposite xe2x80x9cincorrectxe2x80x9d rotational direction, the water in the distal muffler may be forced under its own inertia into the cross-over pipe and then into the proximal muffler. Thereafter, if the watercraft is tipped towards its bow while the operator is remounting the watercraft, the water that has flowed into the proximal muffler may flow forwardly towards and into the two-stroke engine.
Water flowing into the two-stroke engine can detrimentally affect engine performance and may even damage the engine. For example, water (especially salt water) may corrode the engine. The presence of water in the engine may also inhibit oil from adhering to components of the engine and thereby prevent proper lubrication of the engine.
Thus, there is a need for an engine configuration in which the flow of fluids is controlled, especially when the vehicle is not upright.
One aspect of embodiments of the present invention provides an apparatus and method for closing a fluid path when a vehicle flips over so as to substantially prevent undesired fluid flow through the fluid path. For example, if the fluid path is an air escape passage of an oil reservoir of an engine, the fluid path would close when the vehicle flips over to prevent oil from leaking out of the upside-down oil reservoir into the engine or ambient environment. Alternatively, if the fluid path is an engine exhaust system and the vehicle is a watercraft, the fluid path would close when the watercraft flips over to prevent water in the ambient body of water around the watercraft from entering the engine through the exhaust system.
An additional aspect of embodiments of the present invention provides a vehicle that includes a vehicle orientation sensor that generates a vehicle orientation signal, an engine having a fluid path associated therewith, a valve disposed in the fluid path, and a controller operatively connected to the sensor and valve. The controller receives the vehicle orientation signal from the sensor and selectively closes the valve when the controller determines that the vehicle is in a predetermined vehicle orientation.
The vehicle may also include a timer connected to the controller. The controller closes the valve after the vehicle orientation signal indicates that the vehicle is in the predetermined vehicle orientation for a predetermined time period.
According to a further aspect of embodiments of the present invention, the vehicle is a watercraft and the engine includes an exhaust system that defines the fluid path such that closing the valve substantially prevents water from entering the engine by way of the exhaust system. The engine also includes an air intake system that may alternatively and/or additionally define the fluid path such that closing the valve substantially prevents water from entering the engine by way of the air intake system. Furthermore, the engine may also include an oil reservoir. The fluid path has first and second ends, and the first end of the fluid path fluidly connects to the oil reservoir such that closing the valve prevents oil from flowing out of the oil reservoir through the fluid path.
A further aspect of embodiments of the present invention provides a control assembly for a vehicle. The control assembly includes a vehicle orientation condition sensor that generates a vehicle orientation signal based on a direction that the vehicle rolls about its longitudinal axis, a processor operatively connected to the sensor to receive the vehicle orientation signal from the sensor, and an alarm operatively connected to and controlled by the processor. The controller turns on the alarm when the controller determines that the vehicle has rolled in an incorrect direction.
A further aspect of embodiments of the present invention provides a method for selectively preventing undesired fluid flow in a vehicle having an engine and a fluid path associated with the engine. The method includes sensing an orientation of the vehicle, and substantially preventing fluid flow through the fluid path when the sensed vehicle orientation is in a predetermined vehicle orientation. The method may further include sensing that the vehicle is in the predetermined vehicle orientation for a predetermined period of time before substantially preventing fluid flow through the fluid path.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.